Typewriter heater



March 18, 1958 R. CORVINO ET AL TYPEWRITER HEATER 2 Shets-Sheet 1Original Filed June 30, 1952 s R O T m m mw R O C H M R WILLIAM R. STONECHARLES W. PEDERSEN MM; W

ATTORNEY March 18, 1958 R. CORVINO ET AL 2,327,144

TYPEWRITER HEATER Original Filed June 30. 1952 2 Sheets-Sheet 2INVENTORS RALPH CORVINO WILLIAM R. STONE CHARLES W. PEDERSEN ATTORNEYTYPEWRITER smitten Ralph Corvino, Charles W. Pedersen, and William 12.

Stone, New York, N. Y., assignors to Vari-Typer Corporation, acorporation of Delaware Continuation of abandoned application eriai No.296,516, June 39, 1952. This application Ea er-abet 27, 1954, Seriai No.477,955

The terminal portion of the term of the patent to be granted subsequentto December 28, 197d, has been disclaimed 3 Claims. (Cl. 197-65)(Granted under Title 35, U. S. Code (1952), see. ass.)

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

The present application is a continuation of application Serial No.296,516, filed June 3Q, 1952, and now abandoned.

This invention concerns typewriters in particular concerns typewritersin which the type face is heated for making the type impression. ment ofthe invention the type is heated from the back thereof so that theprinted impression can be made upon materials such as thermoplastictubing without excessive heating of the tubing.

In forming printed impressions V by typewriter upon thermoplastic tubingof the kind used as insulation upon electricai conductors, difficulty isencountered in making an impression that is permanent. Impressions madeupon this kind of material a tendency to smear and rub off. it has beenproposed in the past to provide in connection with typewriters of thiskind a heating element located adjacent the type face and the typeribbon and the material upon which the impression is to be made. Thisarrangement has proven unsatisfactory because of the fact that the hightemperatures required in heating the type face result in softening ofthe thermoplastic material to the point where it is fatally damaged.

The present invention overcomes these difficulties by 4 providing inconnection with the kind of typewriter described a heating element thatis disposed behind the type body on the opposite side of the body fromthe type face. The construction is such that the type body forms ashield between the heating element and the material upon which animpression is to be made at the type face. Heating of the type face isaccomplished by conduction from the rear of the type body. The shieldingafforded by the type body prevents overheating of the material uponwhich the impression is to be made.

An object of the invention is to provide a typewriter in which the typeface is heated.

Another object is to provide a typewriter in which the type is heated bya heating element located behind the type body on the side opposite thetype face.

Another object is to provide a typewriter in which the type is heatedfrom behind the type body whereby the type body forms a shield betweenthe heating element and the material upon which the printed impressionis to be made.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. 1 is a top plan view of the rear portion of a type- Writer.

Fig. 2 is a perspective view, with parts omitted and In the prefeuedembodi 2,327,144 Patented Mar. 18, 1958 broken away for clarity, as seenfrom above and to the lower left of Fig. 1.

Fig. 3 is a fragmentary front elevation, with parts omitted for clarity,as seen from the right of Fig. 1, and

Fig. 4 is a wiring diagram of the electrical circuit used in connectionwith the heating element.

In the drawings there is shown a typewriter having a carriage 11 mountedfor movement from left to right and right to left as seen in Fig. 1. Thecarriage 11 is operatively associated with suitable conventionalmechanism (not shown) for progressing it past the printing point 14 asthe individual type selecting levers (not shown) are actuated to affectthe typing operation. A support in the form of an anvil 15 fixed to theframe 16 of the typewriter has a shuttle 17, carrying embossed type,mounted thereon for movement about the periphery of the anvil 15 undercontrol of type keys for presenting selective characters of type at theprinting point 14. A hammer 19 is actuated by a conventional mechanism(not shown) to drive the flexible tube 20 against the selected typecharacter to receive the type impressions. The hammer spring (not shown)is preferably slightly stronger than the standard spring normally usedto supply the necessary force to collapse the tube 20 into a planesurface against the shuttle 17 while forming the printed impression. Aribbon 21 is interposed between the tube 213 and the type shuttle 17 inorder to supply the necessary pigment for forming the type impression onthe tube 20. A conventional ribbon shield 22 is interposed between thetube 24 and the ribbon 21. The shield 22 has an aperture at the printingpoint 14 to permit the tube 21) to contact the ribbon 21 at a pointopposite the selected type on shuttle 17. The shield 22 serves toprotect the tube 20 from marking by the ribson 21 elsewhere than at theprinting point 14. The ribbon shield 22 is conventionally mounted onarms24 and 25 which are fixed in a frame 26 pivoted to the top plate 27of the typewriter.

This general organization of hammer, type shuttle, ribbon and typeshield is old in the art and is shown and described more completely inPatents 2,007,229 of July 9, 1935, issued to Frank H. Trego, and1,936,594 of November 28, 1933, issued to Charles A. Fuchs, to whichreference is made for a more complete disclosure.

The tube 20 is held in position on the carriage 11 by conventionalclamps (not shown). This type of clamp is old in the art and is shownand described more completely in Patent 2,515,381 of July 18, 1950issued to Henry Resch to which reference is made for a more completedisclosure.

According to the present invention, the anvil 15 is heated to anelevated temperature by a heating unit that includes among its elementsa circular, metallic cap 28 mounted on top of the anvil and of theapproximate diameter of the anvil and having 21 depending skirt inthermal contact with the top edge of the anvil throughout itscircumference. The cap 28 is heated to elevated temperature by anotherelement of the heating unit comprising an electrical resistance heatingelement 31 contained within the space defined by anvil 15 and cap 28,the heat of the cap being transmitted to the anvil and in turn to theshuttle 17.

Heating element 31 can be located anywhere within the space defined byanvil 15 and cap 28. For example, heating element 31 can be locatedinside of anvil 15 so that heating element 31 is disposed behind shuttle17 and is on the opposite side of shuttle 17 from the type face. Thusshuttle 17 in effect forms a shield between heating element 31 and tube20 upon which an impression is to be made by the type face of shuttle 17at the printing point 14.

Heating element 31 is generally arcuate in shape. Heating element 31comprises an arcuate tube 32 of suitably refractory material upon whichis wound in the form of a coil an electrical resistance. wire 33 theends 34' and 35 of which are connected in an electrical circuit as laterdescribed in connection with Fig. 4. Refractory tube 32 is'mountcd forsupport upon a core wire 36 the ends of which are bent downwardly at 37with each lower extremity bent into a horizontal loop 38 that isfastened by means of a screw 39 to base 41 forming a part of thetypewriter frame 16. V

The ribbon 21 is a thermosensitive type ribbon that is capable offorming type impressions only when the type, the ribbon and the materialto be typed on, or at least one of them, are at an elevated temperatureso as to soften the ribbon pigment or the surface of the material, orboth for the printing operation. .A single use thermosensitive typeribbon known in the trade as branding tape, which is discarded after onepassage past the printing point'id has proved satisfactory for thispurpose.

The ribbon feed mechanism for progressing ,theribbon 21 past theprintingpoint 14 may be of, any suitable type. The'one shown is similarto thatin Patent 2,161,856 of June 13, 1939, issued to Ralph C. Coxhead,to which reference is made for a more complete disclosure. The ribbon 21is supplied from a conventional spool and is passed through ribbon guide47 and past the printing point 14 adjacent the ribbon shield 22 througha second ribbon guide 48 and between ribbonfeed rolls 51 and '52.

The degree of heat required depends to some extent upon the size of thetype characters being used and upon the particular composition of thematerial upon which the type impressions are to be formed. Variation inheating is provided for by a conventional rheostat 56 mounted at therear of the typewriter and connected in electrical series with theresistance wire 33 of the heating element 31. The rheostat 56 is of theconventional variable resistance type, the amount of electrical currentsupplied to the heating unit 31' being regulated by setting the knob 57in various positions.

To further control the supply of electrical energy to the heating unit31, a conventional off and on electrical snap switch 61 is mounted onframe 16 and connected in series with the rheostat 56 and the heatingunit 31. In

addition, as a safety'precaution a thermostat 62 is positioned adjacentprinting point 14. The thermostat 62 may be of the enclosed conventionalbimetallic element type containing a set of electrical contact points,the action of the thermostat being to open the electrical circuitpassing through the heating unit 31 when the area adjacent heating point14 attains an excessively high temperature.

This thermostat is preferably set to open the circuit upon reaching atemperature .of approximately 275 F. and is in the nature of a safetydevice only, not being operative unless the rheostat-56 is set so as tosupply an excessive amount of electrical energy, all factors beingconsidered,

thus producing ,excessiveheating. of the shuttle 17 and the tube 20 tobetypedJ The electrical connections may be made as shown in Fig. 4, theelectrical system being. connected to a suitable source of electricalpower,customarily 110 volt alternating current. It will be apparent froma studyof Fig. 4 that by maintaining the electrical. switch 61 in anoffposition, the heating unit 31 is not energized. .By substituting. aconventional ribbon for the branding tape previously described,rit ispossibleto usethe same machine for conventional typing on strands ofmaterial and the like which can be suitably engaged by the clamps.

In operation with the electrical system shown in Fig. 4 connected to asuitable source of power, rheostat 56 is set to supply the desiredamount of electrical energy to heating element 31; Snap switch 61 ismoved to'the oil-position and heating element 31 is allowed to heat theshuttle 14 until the type face of shuttle 14 achieves the desiredtemperature. in the event that an excessive temperature at the type faceof shuttle 14 is achieved, thermostat 62 is actuated to open theelectrical circuit of Fig. 4 and thereby tie-energize heating element31.

Because heating element 31 is disposed behind type shuttle I17 and onthe opposite side of type shuttle .17

from the type face, it is seen that heating of the type face is byconduction from the rear of the shuttle. Type shuttle 17 therefore formsa shield between heating element 3?. and tube 20 upon which animpression is to be made at the type face; The shielding afforded byshuttle 17 prevents overheating of tube 24'? and also heating of ribbon21.

Obviously many modifications and variations of the,

present invention are possible in the light of the above teachings. Itis therefore to be understood that within the scope of the appendedclaims the invention may be practiced otherwise than as specificallydescribed.

We claim:

l. in a typewriter for printing with the aid of heat 7 and having athermosensitive type ribbon, an anvil having a cylindrical outersurface, an arcuate type shuttle having type characters embossed thereonand having an arcuate ear surface mounted for sliding movement along theouter surface of the anvil to index selected type at a printing point,and a cylindrical heat-control unit mounted above the anvil andcomprising a cylindrical, metallic cap having a generally fiat, circularportion and having a de- I pending, cylindrical skirt in thermal contactwith the anvil throughout its circumference, and an electricalresistance heating coil mounted within the space defined by the cap andanvil.

2. In a typewriter for printing with the aid of heat and having athermosensitive type ribbon, an anvil having a cylindrical outersurface, an arcuate type shuttle having type characters embossed thereonand having an arcuate rear surface mounted for sliding movement alongthe outer surface of the anvil to index selected type at a printingpoint, and a cylindrical heat-control unit mounted above the anvil andcomprising a cylindrical, metallic cap having a generally iiat, circularportion and having a depending, cylindrical skirt in thermal contactwith the anvil throughout its circumference, and an electrical heatingmeans mounted Within the space defined by the cap and anvil for heatingthe anvil and shuttle.

3. In a typewriter for printing with the aid or heat and having athermosensitive type ribbon, ananvil having a cylindrical outer surface,an arcuate type shuttle having type characters. embossed thereon andhaving an arcuate rear surface mounted for sliding movement along theouter surface of the anvil to index selected type at a printing point,and a heat-control unit mounted at the anvil and comprising a metalliccap covering the .anvil and having a depending circular skirt in thermalcontact with the anvil throughout its circumference, and an electricalresistance heating unit mounted in the spacev defined by the cap andanvil for heating the cap, anvil, and shuttle.

References Cited in the file of this patent UNITED STATES PATENTS1,300,342 Campbell Apr. 15, 1919 1,714,795 Luedtke et al. May 28, 19292,515,381 Resch July 18, 1950 2,664,184 Johnson Dec. 29, 1953

